1. Field of the Invention
The invention concerns a method and apparatus for operating an internal-combustion engine, and particularly an Otto engine employing a reformed-gas generator.
2. Description of the Prior Art
A method for operating an internal-combustion engine (hereafter referred to as "engine") particularly an Otto engine, utilizing a reformed-gas generator (hereinafter referred to as "gas converter") is already known from U.S. Ser. No. 218,696. In the method described therein, atomized or evaporated, hydrocarbon-containing fuel is fed, with an appropriate admixture of air and/or exhaust gas fed back from the engine, to the reaction chamber of the gas converter. There the mixture is converted at a catalyst, raised to a suitable elevated temperature, into a fuel gas mixture containing methane and carbon monoxide and possibly also hydrogen. This is then fed, with the admixture of additional air, to the combustion chambers of the engine. Catalysts suitable for use in the gas generator just mentiond can be the nickel or platinum catalysts mentioned in U.S. Ser. No. 218,696, or the oxide catalysts, such as those disclosed in the U.S. Ser. No. 334,932, or the U.S. Ser. No. 336,062. Use of any of the catalyst carries just enumerated makes possible a very compact design of the converters, making them suitable for installation in motor vehicles. The fuel gas generated in the converter has a high octane number and can be burned in the combustion chambers of the engine with considerably less harmful and environment-polluting residues than the liquid fuels which are customarily burned. Liquid fuels most suitable for conversion in the gas generators are those which are low in harmful substances such as lead, cyclic hydrocarbons and sulfur. Additives which increase the octane number and have a harmful effect particularly in the exhaust gases are not required in the liquid fuels that are to be used. The fuel gas mixture generated in the reformed-gas generator already has a high octane number, as already mentioned.
For proper utilization of the gas generator as a source of fuel for the engines, favorable apportioning of the substances, i.e., fuel, air and fed-back exhaust gas, participating in the reaction in the gas generator is particularly important.
In the U.S. Ser. No. 270,923, a method for apportioning the quantities of fuel, air and fed-back exhaust gas necessary for maintaining a predetermined operating temperature in the reaction chamber of the gas converter is disclosed. By different apportioning of the shares of air and exhaust gas in the air-exhaust gas mixture mixed with the fuel the temperature in the reaction chamber of the gas generator can be controlled, since the reaction of the fuel with the air takes place essentially exothermically, while the reaction of the fuel with the exhaust gas essentially endothermically. The temperature of the reaction chamber of the converter serves as the control quantity for the apportionment of the quantities of air, fuel and exhaust gas which are to be supplied to this reaction chamber. However, the fuel requirement of the engine is provided through the control of a fuel metering device which responds to the position of the throttle.
It is an object of the invention to provide a method and means for providing improved utilization of the fuel used, resulting in the greatest possible reduction of harmful substances to be emitted by the exhaust gas.
It is an additional object of this invention to provide a method and means whereby the apportioning of fuel, air and/or exhaust gas supplied to the gas generator is a function of the fuel demand requirements of the engine.